39 
11. Variation in the character of plants according to 
locality, even within the zone in which they are indigenous* 
is a phenomenon familiar to all. When those of one zone are 
transferred to one more torrid, or one more frigid, whether 
by reason of latitude or elevation, changes in character, as in 
appearance, become still more defined.* Even in Britain the 
same species presents very different characters, according to 
its position in these respects. Trees, shrubs, and other plants, 
introduced from climates more or less closely approximating 
to that of these islands, in many instances refuse to propagate 
their kind. In some of these inflorescence does not take 
place, in others the flower drops to earth or withers, but 
without producing fruit ; in others there is, for a time, a 
promise of fruit, but soon the seed vessels die away, and 
gardeners, when they desire to propagate the species, are 
only able to do so by “ slips/* In other instances the pro- 
perties of plants become altered; in others the species 
flourishes for a time, then gradually fades, and becomes extinct* 
In man analogous phenomena to some extent occur. And yet 
there are phenomena in relation to the distribution of plants 
which are unaccounted for by conditions of climate alone* 
Thus, localities the “ climate ” and rainfall of which are nearly 
as possible alike, have not necessarily identical floras,, any 
more than identical faunas. Certain plants also have only a 
local distribution. For example. Erica vagans , or Cornish 
heath, on soil of broken down serpentine ; Cypripidium, or 
lady*s slipper, on alpine limestone in the Swiss Alps. The 
Oxytropis campestris is confined to one spot on the Clova 
hills. Cotoneaster vulgaris is, in Britain, found onty on 
the limestone cliffs at Great Orrae^s Head, in Wales. Poten -_ 
tilla rupestris, in Britain, only on the Breddin Hills, in Mont- 
gomeryshire. A flowering plant may be found in the arctic 
and temperate regions, and then reappear in the southern 
temperate and antarctic regions, but none range from pole to 
pole. Every species which at once exists on two continents 
is also found on the intermediate islands. 
* The American water-weed ( Anacharis ), first introduced into this country 
in 1847, has spread with great rapidity, expelling the native species, with 
which it came in contact, though it has never yet produced seed. In America 
it is not more troublesome than other weeds. In the Neilgherry Hills the 
Lantana threatens to choke the coffee on some plantations. In New 
Zealand the Rumex acetocella and the cat’s ear ( Hypocharis radicata ) are 
destroying native pastures. The spread of Vallisneria in the Hudson is as 
extensive as that of Anacharis in Britain. — Daubepey on, Climate, p, 73.. 
